A nurse is preparing to administer the first dose of cefazolin via intermittent IV infusion to a client. Which of the following actions should the nurse take first?

Rationale: A. Check the compatibility of cefazolin with the client's existing IV fluids: Compatibility is important to prevent precipitation or inactivation of the drug, but it should be done only after confirming the medication is safe for the client to receive. B. Assess the IV for patency: Ensuring the IV line is patent is necessary before administration to avoid infiltration or extravasation, but it is not the first priority when preparing a first-time antibiotic dose. C. Review the client's allergy history: Reviewing allergies is the first and most critical step, as cefazolin is a cephalosporin that can cause severe allergic reactions, particularly in clients with a history of beta-lactam (e.g., penicillin) allergy. Administering the drug without this check could cause life-threatening anaphylaxis. D. Obtain the reconstituted antibiotic from the pharmacy: Securing the medication from the pharmacy is part of preparation, but this should only occur after confirming it is safe for the client to receive based on allergy status.